Process of making chlorosulphonic acid



A Patented Sept. 22, 1925.

..,]UNITED STATES,

PATENT OFFICE.

RALPH a. mm m) cannon. m. SALLS, or new roux, N. Y.

PROCESS OF MAKING CHLOROSULPHONIC ACID.-

' No Drawing.

ticularly to the manufacture of chlorosulphonic acid by means of a catalyst.

If known methods of making chlorosulphonic acid, sulphur trioxid is treated with dry hydrogen chlorid or dry hydrochloric acid is run into oleum and the resultlng product distilled.

Theoretically, chlorosulphonic acid may be expected to be produced when sulphuryl chlorid is treated with sulphuric acid according to the following equation;

' current of sulphuryl chlorid vapor passed may be caused to react to-produce chlorosulphonic acid.

In the present inventionpwe employ a catalyst, such as mercury, salts of mercury,

and other catalysts of the same general type,

such as antimony, tin or bismuth; The. sulphuryl chlorid and sulphuric acid andthe catalyst aremixed in the proper proportions and heated in a closed vessel to pro- I duce a homogeneous mixture,.which is then distilled to separate the chlorosulphonic acid from the remaining sulphuryl chlorid, sulphuric acid and the catalyst.

' In another form of the invention, the catalyst is placedin the sulphuric acid and a through the hot acid. The resulting distillate is condensed and then redistilled and impurities separated from the; chlorosul phonic acid formed.

In a typical embodiment of jthe invention,

, sulphuric acid of approximately 100 per cent strength is employed. The use of 100 per cent sulphuric acid is not essential, although Application filed June 20, 1923. Serial No. 646,658.

preferred. If a weaker acid is used, there is a slight loss in the yield of chlorosul-' phonic acid due to its reaction with the water inthe sulphuric acid to produce additional sulphuric acid'and hydrochloric acid. 140 parts by weight of sulphuric acid and 100 parts of sulphuryl chlorld, together with 2.4 parts of mercury are heated in a closed vessel to a temperature of approximately 160 C. for a period of about 8 hours and the resulting homogeneous mixture is then distilled. This produces substantially 160 parts of chlorosulphonic acid, a trace of sulphuryl chlorid, and a residue of parts of sulphuric acid containin the mercury added as a catalyst, largely m-the form of mercuric sulphate. This jresidue may be employed in the next charge in place of a similar amount of sulphuric acid. J

When sulphuryl chlorid vapors is employed, strong sulphuric acid containing from to per cent ofits weight of mercury, is

heated to a temperature between 200 C. to 300 C., and. a current of sulphuryl chlorid vapor passed through the .hot'acid. The

resulting distillate is condensed and then, redistilled. The second distillate. is condensed by a primary condenser. The uncondensed xvapor contains sulphur dioxid, chlorine andsulphuryl chlorid. ,These vapors are passed into a cooled vessel .carry- J ing active carbon and the sulphur dioxid and chlorine are combined to form additional sulphuryl chlorid which may be reused; in the process. While a temperature are obtained when a temperature of substantially 250 C. is used. The higher the temperature, the higher the rate of reaction of the sulphuryl chlorid, 'buta higher temrunning from 200 to 300 'C. may be em-. ployed, weghave found that the best results perature has the disadvantage that larger amounts of sulphur dioxid and chlorine are formedby the decomposition of the sulphuryl chlorid b 'heat. However, even at a temperature 0 300 C., this discomposition is not excessive or sufficient to cause trouble in carrying out. the process, The loss of catalyst is small from a commercial viewpoint, a small part of it distilling over with the chlorosulphonic acid.

7 In practicing the process, wherein sulphuryl chlorid vapor is added to hot sul pliuric acid, the reaction may be carried out as a plant process of the continuous type curic chlorid and we have found that salts of antimony, tin or bismuth which are commonly used as catalysts may also be employed, but mercury and the mercuric salts are preferred to the other salts mentioned.

While we have described in detail the preferred practice of the process, it is to be understoodthat the details of procedure, and pro ortion of ingredients may be widely varied, and that known chemical equivalents may be employed in place of the materials mentioned, without departing from the spirit of the invention or the scope of the subjoined claims.

We claim:

1. The process of making chlorosulphonic acid which comprises heating sulphuryl chlorid and sulphuric acid in the presence of a catalyst.

2.v The process of making chlorosulphonic acid which comprises heating sulphuryl chlorid and sulphuric acid in the presence of a mercury compound.

3. The process of making chlorosulphonic ,acid which comprises "heating sulphuryl chlorid and sulphuric acid in a closed vessel in the resence of a catalyst.

4. T e process of making chlorosulphonic acid which comprises heating sulphuryl chlorid and sulphuric acid in a closed vessel to a temperature of substantially 160 C. in the presence of a catalyst.

5 The process of making chlorosulphonic acid whichcomprises heating a body of sul phurlc acid containing a catalyst, passing sulphuryl. chlorid vapors into the heated acid and collecting the chlorosulphonic acid vapors formed.

6} The process of making chlorosulphonic acid which comprises heating a body of sulphuric acid containing a small quantity of a mercury compound, passing sulphuryl chlorid vapors into the heated, acid and collecting the chlorosulphonic acid vaporsformed.

7. The process of making chlorosulphonic acid which comprises heating a body of sulphuric acid containing a catalyst, adding sulphuryl chlorid thereto, heating the mixture to form chlorosulphonic acid vapors, and collecting the vapors formed.

8-. The process of making chlorosulphonic acid which comprises heating a body of sulphuric acid containing a catalyst, adding sulphuryl chlorid to the body of sulphuric acid at intervals, and continuously collecting the va ore of chlorosulphonic acid formed.

9. T e process of making chlorosulphonic acid which comprises heating sulphuryl chlorid and sulphuric acid in the presence of a catalyst, collecting'the distillate, redistilling it -and passing the vapors through carbon to cause the sulphur dioxid and chlorine present in said vapors to react and form sulphuryl chlorid.

10. The process of phuric acid containing a catalyst, adding sulphuryl chlorid to the heated acid, col- 'lecting' the vapors'of chlorosulphonic acid,

condensing said vapors, redistilling said chlorosulphonic acid, and collecting the vapors to obtain substantially pure chlorosigna- RALPH H. MoKEE. *GARROLL M. SALLS.

making chlorosulphonic acid which comprises heating a'body of sul-. 

